1. Field of the Invention
The present invention relates generally to electrical connector shield cases, especially to an electrical connector shield case for enclosing the insulation member of a plug connector or receptacle.
2. Description of the Prior Art
FIGS. 8 and 9 show a conventional electrical connector shield case consisting of front and rear case sections 10 and 20. The front or rear case section has a cylindrical shell 13 or 23 and a transverse flange 11 or 21. These case sections 10 and 20 are joined together by putting the transverse flanges 11 and 21 together with screws, for example, to enclose an insulation block 40 on which male contacts 30 are planted.
These shield case sections 10 and 20 have been made of a sheet of metal. A method of making the front shield case section 10 will described with reference to FIGS. 10A through 10E.
(1) As FIG. 10A shows, a rectangular piece of metal 10A sufficiently large to meet the size of a final product or front case section 10 such as shown in FIG. 8 is prepared.
(2) As FIGS. 10B and 10C show, a lower die 50 with a protuberance 51 having a section similar to that of the shell 12 is pushed upwardly into an upper die 60 with a depression 61 to draw a case element 10B having a crown portion 11B and a brim portion 12B such as shown in FIG. 10D.
(3) As FIG. 10E shows, a lower die 70 with a protuberance 71 having a section similar to that of the crown 11B and a depression 72 corresponding to the periphery of the flange 11 of the front case section 10 and an upper die 80 with a depression 81 having a section similar to that of the crown 11B and a protuberance 82 corresponding to the periphery of the flange 11 of the front case section 10 are relatively moved toward each other to form an opening 13 on the top of the crown 11B and the desired flange 11 as shown in FIG. 8.
(4) As FIG. 11 shows, a plurality of front case sections 10 are hung from a hanger 92 and dipped in the plating liquid 91 of a plating tank 90 for plating. The rear case section 20 may be made in the substantially same manner as that of the front case section 10 and its description will be omitted.
As FIG. 8 shows, the insulation block 40 is placed between the front and rear case sections, fitted into the opening 23 of the rear case section 20 and then covered by the front case section 10. The front and rear case sections 10 and 20 are put together by inserting a pair of studs 24' with a through hole 24 through a pair of apertures 14 in the front flange 11 and deforming them (FIG. 9).
The above electrical connector shield case, however, has the following shortcomings.
(1) The above drawing process reduces the yield of a metal sheet and increases the material cost.
(2) The respective steps of the above manufacturing process are completely separated and are difficult to use in a continuous production line, thus increasing the unit manufacturing cost.
(3) The drawing process requires a soft and extensible metal, putting a limit on the range of choices in material and pushing up the unit manufacturing cost. The soft material is also liable to deformation by an external force.
(4) The height of a shell drawn is so large that the thickness of the shield case becomes uneven, thus reducing the product precision.
(5) In order to make a good shield contact between two connectors, it is often necessary to make some projections on the outside or inside of the case surface. These projections are very difficult to make by drawing.
(6) For plating, each case has been hung manually on the hanger, reducing the production efficiency and increasing the unit manufacturing cost.
(7) For assembly of a shield case around an insulation block has been made manually and is very difficult to mechanize, increasing the unit manufacturing cost. This manual operation also brings about a dispersion in the product quality.